The present invention concerns a time sharing device for access to a principal memory connected to a single bus between a central computer and a plurality of peripheral computers.
Such a device is particularly useful in installations including several rapid peripheral computers, particularly for the transmission of data. In such installations, in order to permit a central control computer to be free to execute a recorded control program, a plurality of peripheral exchange units are used. Each peripheral unit contains a low capacity, programmed peripheral computer which performs elementary functions at a local level.
These peripheral computers must, from time to time, have access to a principal memory, for example for the exchange of information with the central computer or other peripheral computers.
The principal memory is then connected to a single bus and a time sharing device is used to control access to the main memory.
Such devices are generally complex, expensive and slow. It is the object of the present invention to eliminate these disadvantages.
The device according to the present invention comprises a searching circuit to detect a peripheral computer that has requested to be connected with the single bus for access to the principal memory, and a decision circuit for authorizing the peripheral computer requesting access to the principal memory to connect to the single bus when access to the bus is possible.
The searching circuit is connected bidirectionally to the different peripheral computers and to the decision circuit. The decision circuit is also connected bidirectionally with the different peripheral computers and the central computer.